1. Field of the Invention
This invention relates generally to venting systems for drain lines, and pertains more particularly to an improved anti-siphoning device therefor.
2. Description of the Prior Art
In household plumbing, a roof vent or stack pipe is normally required to prevent sewer gases from flowing upwardly through the drain line into the dwelling via the sink or basin. Stack pipes have posed a serious problem, particularly where modern-day households make use of a number of lavatories, because each sink or other item to be drained requires a stack pipe, or if a single vertical stack or venting pipe is employed, then lateral runs must be employed in order to connect the various appliances to be drained to the centrally located stack pipe. Even the incorporation of a single stack or vent pipe can be quite costly, and when additional stack pipes must be employed, or lateral connections made to a centrally located stack pipe, the installation costs become quite significant.
The problem has been recognized for a number of years. In this regard, my previously issued U.S. Pat. No. 3,107,682, granted on Oct. 22, 1963 for "Ventillating System" effectively eliminates the need for a stack pipe. While my patented invention has performed admirably, nonetheless I have now devised an improved anti-siphoning device, the present device possessing various improved features over my previous system.